package demo3;

public class Computer {
    public void open(){
        System.out.println("打开电脑");
    }
    public void close( ){
        System.out.println("关闭电脑");
    }
    public void useUSBDevice(USB usb){
        usb.openDevice();

        if(usb instanceof Mouse){
            Mouse mouse=(Mouse)usb;
            mouse.click();
        }else {
            Keyboard keyboard=(Keyboard)usb;
            keyboard.input();
        }
        usb.closeDevice();
    }

}
